Lag-screw



1 (No Model) I G. P. RO$E.

LAG SCREW. No. 408,751. Patented Aug. 13, 1889.

UNITED STATES PATENT OFFICE.

GEORGE PAYNE ROSE, OF FENTQN, MICHIGAN.

LAG-SCREW.'

SPECIFICATION forming part of Letters Patent No. 408,751, dated August13, 1889.

Application filed November 21, 1888. Serial No. 291,434. (No model.)

To all whom it may concern.-

Be it known that I, GEORGE PAYNE RosE, a citizen of the United States,residing at Fenton, county of Genesee, State of Michigan, have inventeda new and useful Lag-Screw, of which the following is a specification.

The object of this invention is to constructa lag-screw having apeculially-constructed threaded portion above the point and a headshaped angular to form a wrench-seat, as be low set forth and claimed.

In the drawings forming a part of this specification, Figure 1 is asideelevation looking from a point at the right of Fig. 2, and Fig. 2 is anelevation looking from a point at .the left of Fig. 1.

Referring to the letters marked on the drawings, B is the lag-screw,having an angular head 0 and a long plain body portion below said head,forming a bearing in the wood when the screw is turned, and ascrew-threaded portion flattened on two opposite sides below the plainbody portion.

The threaded part c of the lag-screw is in the main circular incross-section, but has flat tened sides. The spiral threads at are thuson two opposite sides only, the other two opposite sides being fiat, asin Figs. 1 and 2. The surfaces between the separated threads of theportion e forthe most part at least are vertically straight. However,said screwthreaded body 6 may be greater in diameter at the upper end S,and from thence gradually taper for a short distance, as in Fig. 1, togive greater strength at this point; but this is a matter of choice. Theupper faces of the threads are at right angles to the body e and beveledon the under side.

The point of the lag-screw is wedge-shaped with two diagonallyoppositeedges chamfered off at r 'r to facilitate turning after the lag-screw isdriven. The lower end may be conical-pointed, instead of wedge-shaped,ifpreferred.

In the use of the lag-screw it is driven like a nail with a hammer, thelong way of the wedge end being crosswise of the grain of the Wood intowhich it is driven. The lag-screw is then given a quarter-turn with awrench, which action takes the threads 0. out of the wood broomed bythem when driving the lagscrcw, and forces them into the solid wood,which was at the fiat sides before the lagscrew was turned. By theexpression broomed. I mean the condition of the Wood on the threadedsides of the lag-screw, which is broken and left splintered or ragged bythe threads being forced through the wood when the screw is driven witha hammer. This action is not here shown, but will be readily understood.

It will be observed that in Fig. 1 the grooving of the threads extendsonto the beveled part of the wedge-point. This facilitates turning thelag-screw after it is driven.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

A lag-screw having a square head for the attachment of a wrench thereto,said screw being flattened and having threads on two opposite sides, theupper sides of said threads being at right angles to the screw-body andhaving vertically-straight intermediate sur- GEORGE PAYNE ROSE.

Witnesses:

ARTHUR M. RAIsoM, J. L. HAWES.

